It has long been desired to maximize fuel economy, power and driveability in fuel powered vehicles while enhancing acceleration, reducing emissions, and preventing hesitation. Over the years, detergent compositions for fuels have been developed. Detergent compositions known in the art for use in fuels include compositions that may include polyalkylene succinimides, polyamines and polyalkyl substituted Mannich compounds. Detergents are suitable for keeping soot and sludge suspended in a fluid, however the foregoing detergents are not particularly effective for cleaning surfaces once deposits have formed on the surfaces.
Fuel compositions for fuel injected engines often produce undesirable deposits in the internal engine surfaces and fuel filters. Improved compositions that can prevent deposit build up or clean out deposits from engine parts are highly desirable. Some additives that may be effective for improving power recovery in engines may be detrimental to fuel injectors, causing injector sticking. Accordingly, improved compositions that can prevent deposit build up and prevent injector sticking, as well as restore engine power are highly desirable. Ideally, the same composition that can clean up dirty fuel injectors restoring performance to the previous “as new” condition would be equally desirable and valuable in the attempt to reduce air borne exhaust emissions from the engines.
Quaternary ammonium salts are known effective detergents to clean out undesirable engine deposits. For example quaternary ammonium salts derived from the reaction of a tertiary amine compound with certain aromatic esters are good detergents. Alkoxylated quaternary ammonium compounds are particularly effective as fuel detergents. However there is still a need for quaternary ammonium additives that are not only effective as fuel detergents but also have improved handling properties and package stabilities.
For example, certain alkoxylated quaternary ammonium compounds are very polar and have limited solubility in hydrocarbon fuels. Some quaternary ammonium compounds are highly viscose or pasty materials that require special handling, such as heating, in order to provide a fuel additive package. Synthesis of such alkoxylated quaternary ammonium compounds often requires the presence of alcoholic solvents which not only may need to be removed subsequently to making the additive but the alcoholic solvents may also cause unnecessary side reaction products during the synthesis steps. Accordingly, there continues to be a need for fuel additives that are effective for improving the power performance of engines, without causing fuel injector sticking and that can be incorporated into a fuel composition without special handling and that can have better package compatibility and stability.
In accordance with the disclosure, exemplary embodiments provide a fuel soluble additive for a gasoline or diesel engine, a fuel containing the additive, a method for improving performance of fuel injectors and a method for cleaning fuel injectors for an engine. The fuel soluble additive includes an esterified quaternary ammonium salt derived from a tertiary amine, an epoxide, a proton donor and an anhydride. In another embodiment, the ester of alkoxylated quaternary ammonium salts may be substantially devoid of hydroxyl groups.
Another embodiment of the disclosure provides a method of improving the injector performance of a fuel injected engine. The method includes operating the engine on a diesel fuel composition containing a major amount of diesel fuel and from about 5 to about 100 ppm by weight based on a total weight of the fuel composition of an esterified quaternary ammonium salt derived from a tertiary amine, an epoxide, a proton donor selected from a carboxylic acid and an alkyl phenol and an anhydride.
A further embodiment of the disclosure provides a method for making an esterified quaternary ammonium salt fuel additive. The method includes reacting a tertiary amine in the presence of an epoxide, a carboxylic acid and an anhydride.
In another embodiment of the fuel additive, the tertiary amine is an amido amine is derived from a fatty acid.
An advantage of the fuel additive described herein is that the additive may not only reduce the amount of deposits forming on fuel injectors, but the additive may also be effective to clean up dirty fuel injectors sufficient to provide improved power recovery to the engine. Other advantages of the additives described herein are that the additives do not require the presence of an alcohol solvent that must be removed subsequent to the synthesis step and the additives are more readily soluble in fuels and fuel additive compositions without special handling techniques.
Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.